ERYTHRODIPLAX., 247 
the first species listed by Brauer! under the name LErythrodiplax. Under present 
rules, Mr. Kirby’s designation should stand. 
Certain venational characters, usually considered to be of generic value in the 
Libellulinz, are quite variable in this genus, so that I cannot regard some of them as 
even of specific importance. Thus, E. berenice usually has the sectors of the triangle 
arising separated from each other by a distinct interval, but 12 per cent. of the hind 
wings of twenty-five individuals have these sectors arising from the same point. 
Brazilian individuals of HE. minuscula have these sectors separated at origin, but a 
majority of those examined from Florida have their points of origin coincident. 
Certain forms of E. connata, as those listed posted as d and d’, vary, often asym- 
metrically, in the number of cells between the posterior angle of the triangle and the 
distal subbasal sector (A, of C. & N.) immediately opposite, on the hind wings. 
Li. ochracea and E. connata & and a! vary in the number of post-triangular rows on 
the front wings; E. connata e (fusca, Ramb.) is very variable asymmetrically in the 
same area of the hind wings. De Selys* and Dr. Ris‘ have compared members of 
this group with the Old World species known since 1868 as Crocothemis, Brauer. 
No extended comparison has yet been published, but one distinctive feature may be 
mentioned. Crocothemis has on the anterior surface of the frons a pair of triangular 
flattened areas wanting in Erythrodiplar. Diplacodes, Kirby, is a genus whose 
type-species is from Madagascar, but one of our present fauna, here listed as 
Erythrodiplax minuscula, has been referred to it. Until the Old World species are 
studied more carefully, the relations of Diplacodes to Erythrodiplax must remain 
doubtful. 
Some references in literature to certain of the species herein treated are purposely 
omitted on account of the uncertain nature of the identifications on which they are 
based. 
Contrary to the practice adopted in other genera of this subfamily treated in this 
work, the dimensions of the species are given in the body of the text instead of in the 
synopsis of the species. | 
Synopsis of the Mexican and Central-American Species. 
A. Wings with two rows of cells between the subnodal sector and the supple- 
mentary sector next below. Sectors of the triangle, hind wing, arising 
from the same point. Two colour-forms of females in each species, the 
wings of one coloured like (homceochromatic ?), of the other coloured 
unlike (heterochromatic 9), those of the male. 
* In Sagra’s Hist. Cuba, Insectes, p. 451 (1857). 
+ Rambur has mentioned these in his description of Libellula ferruginea (= Crocothemis erythraa, Brullé) : 
the frons “ ayant antériearement deux large impressions” (Névrop. p. 79, 1842). 
